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Rash

Medically reviewed by Drugs.com. Last updated on Jan 3, 2024.

What is a Rash?

Harvard Health Publishing

A rash is a temporary eruption or discoloration of the skin and is often inflamed or swollen. Rashes come in many forms and levels of severity, and they last for different amounts of time. Some common causes of rashes include the following.

Infections 

This broad category covers a wide range of illnesses, including:

Rash

Allergic reactions

These can be triggered by: 

Local irritants 

This category includes diaper rash (caused by prolonged skin contact with urine and stool) and rashes caused by contact with harsh chemicals, such as laundry soaps and fabric softeners.  

Poisonous plants

 Poison ivy, poison oak and poison sumac share a highly allergenic sap resin that can cause allergic rashes in 70% of people exposed to it. 

Autoimmune disorders

This category includes systemic lupus erythematosus (SLE or lupus), dermatomyositis and scleroderma, disorders in which the body's immune defenses mistakenly attack healthy areas of the body, including the skin.

Symptoms

Although rash is easily recognized, all rashes are not the same. Rashes vary in their appearance, timing, location or distribution, and duration. In general, rashes can be described as: 

Additional signs and symptoms that sometimes accompany rashes include: 

Diagnosis

Your doctor will ask you about your medical history, including your history of allergies and your work history, to check for possible exposure to chemical irritants or to people with infections. Your doctor also may ask specific questions about your rash, including: 

Your doctor may suspect a specific cause based on your medical history and the history of your rash. Your doctor will try to confirm this suspicion by examining the rash's appearance, location, pattern and any associated symptoms. In many cases, the results of your physical examination will clarify the diagnosis, and no further tests will be needed. 

When required, additional testing may include: 

Expected Duration

How long a rash lasts depends on its cause. However, most rashes usually disappear within a few days. For example, the rash of a roseola viral infection usually lasts 1 to 2 days, whereas the rash of measles disappears within 6 to 7 days. Rashes caused by an antibiotic allergy may last 3 to 14 days, whereas diaper rash almost always clears up within 1 week (if diapers are changed frequently). 

Rashes resulting from lupus or dermatomyositis may last for an extended period of time.

Prevention

Prevention depends on the cause of the rash: 

Treatment

Treatment depends on the cause of the rash: 

Treatment options

The following list of medications are related to or used in the treatment of this condition.

View more treatment options

When To Call a Professional

Seek immediate medical attention if you begin to have difficulty breathing or develop hives, a fever, a fast pulse, confusion or nausea. These could be signs of a life-threatening allergic reaction.  

Always consult your doctor promptly if a rash: 

Prognosis

The outlook for most rashes is excellent, especially after the cause has been identified accurately.  

In severe allergic reactions, a patient can die within minutes without immediate medical treatment. With proper treatment, recovery usually is complete. However, the patient remains at risk of future severe reactions if he or she is exposed to the same allergy-producing agent. For this reason, a prescription for a self-injection pen containing epinephrine for emergencies usually is recommended for people with severe allergies.  

For long-term autoimmune conditions, rash is only one of a wide variety of symptoms. The prognosis depends on the type and severity of the autoimmune disease. 

Additional Info

National Institute of Arthritis and Musculoskeletal and Skin Diseases
National Insitutes of Health
https://www.niams.nih.gov/

American Academy of Dermatology
https://www.aad.org/

American Academy of Allergy, Asthma & Immunology (AAAAI)
https://www.aaaai.org/

The Food Allergy & Anaphylaxis Network
https://www.foodallergy.org/


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Treatment options

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.